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Experts urge against making health decisions based on DIY genetic tests

Results can lead to unnecessary worry or be wrongly reassuring

Emily Perryman | 18th October 2019

The public is being urged not make health decisions based
on genetic tests they do at home.

A team of experts from the University of Southampton
warned that the results can be unreliable – either wrongly reassuring or
leading to unnecessary worry.

23andMe, one of the companies offering tests, said there
were “many cases” where results had

Prof Anneke Lucassen, president of the British Society
for Genetic Medicine and a consultant in clinical genetics at University
Hospital Southampton, said genetic tests sold online and in shops “should
absolutely not be used to inform health decisions without further scrutiny”.

She said finding a health risk via the tests often does
not mean a person will go on to develop the health problem in question, while
reassuring results might be unreliable.

Some patients’ tests wrongly indicated they had faulty
genes suggesting a high risk of certain cancers.

The BMJ paper warns genetic tests often prioritise
“breadth over detail”, citing a 23andMe test that checks for a few
variants of Brca1 and 2, linked to breast and ovarian cancer risk, when there
are actually thousands.

A 23andMe spokesman told BBC News its processes were
extremely accurate and it spelt out exactly what its Brca test looked for.

“We are very clear with customers that we test only
for certain genetic variants,” he said. “As far as the variants we
are testing for, they are some of the most well studied and associated with
extremely high risk.”

He added that there have been many cases where customers
have taken a 23andMe result to their doctors, been prescribed confirmatory testing
and have had preventative treatment as a result.

Dr Helen Wallace, director of GeneWatch UK, said:
“We recommend that you do not buy these tests, which are at best a waste
of money. Handing your DNA to a private company also raises privacy concerns for
you and members of your family.”